Instrumentation

Breath Analyzer

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Breath analyzer

Introduction: A breathalyzer is a device for estimating blood alcohol content (BAC) from a breath sample. Breathalyzer is the brand name of a series of models made by one manufacturer of breath alcohol testing instruments and is a registered trademark for such instruments. In Canada, a preliminary non-evidentiary screening device can be approved by Parliament as an approved screening device, […]

Instrumentation

Laser Doppler Velocimeter (LDV)

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LDV

Doppler Effect Statement: The Doppler effect, named after Austrian physicist J. C. Doppler who first described it for sound in 1842, states that “The waves emitted from a source moving toward an observer are squeezed; i.e. The wave’s wavelength is decreased and frequency is increased,” as shown in the schematic below. Conversely, waves emitted from […]

Instrumentation

Anemometer

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Anemometer

Introduction: The term is derived from the Greek word anemos, meaning wind. An anemometer is a device for measuring wind speed, and is a common weather station instrument. The first known description of an anemometer was given by Leon Battista Alberti around 1450. Anemometers can be divided into two classes: those that measure the wind’s […]

Electronics

TEMPERATURE CONTROLLED DC FAN (Thermister Characteristics)

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Circuit diagram of temperature control DC fan

Heat Sensor: Temperature controlled DC fan is a temperature based fan. It can cool the devices by operating a DC fan when the temperature in its vicinity increases above the preset level. Its operation is fully automatic and turns off when the temperature returns normal. Components  Required: —Resistors  (4.7kΩ) —Op Amp (LM 358) —Transistor (BC […]